1. Field of the Invention
The present invention relates to a toner cartridge and an image forming apparatus, such as an electronic copying machine having a toner cartridge, and more particularly to a toner cartridge having a mechanism for preventing toner from cohering into a solid mass, and an image forming apparatus provided with this toner cartridge.
2. Description of the Related Art
An image forming apparatus such as a desk-top copier has a developer unit, which has toner supply means for supplying toner, i.e., an agent for developing images. The toner supply means can be of the known type including a toner cartridge. When the toner cartridge becomes empty, it is replaced by a new one, filled with toner.
U.S. Pat. No. 4,686,934 discloses a toner cartridge which comprises a housing containing toner and having a toner supply port, a toner transport auger for transporting the toner to the toner supply port, and toner-stirring means for stirring the toner, thus preventing the toner from cohering into a solid mass. The toner-stirring means comprises a stirring paddle, a first gear integrally formed with the stirring paddle, and a second gear integrally formed with the toner-transport auger and set in mesh with the first gear. When the toner-transport auger is driven by drive means (not shown), the second gear rotates the first gear, thereby rotating the stirring paddle. As a result, the paddle stirs the toner contained in the housing of the cartridge.
Since the stirring means has a complex structure, its production cost is high. Further, any part of the toner which is located outside the locus of the stirring paddle cannot be stirred at all. In order to stir all toner within the housing, the shape and size of the housing are both limited, and so is the amount of toner which the housing can contain. Thus, the toner cartridge must be replaced by a new one after a relatively short period of time. In other words, the cartridge cannot last a sufficiently long time, and is therefore uneconomical.